body {
    font-family: Arial, sans-serif;
    text-align: center;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
}

header, nav, main, footer {
    width: 80%;
    max-width: 800px;
}

nav ul {
    list-style-type: none;
    padding: 0;
}

nav li {
    display: inline;
    margin: 0 10px;
}